Abstract:

A puller is provided with a number of advantages. Pullers are described
that have a high power to weight ratio, and a high power to volume ratio.
Examples of pullers and pulling systems include configurations that
provide high cable friction in a small device volume. Examples of pullers
and pulling systems also include constant force pulling which is
desirable in particular for small diameter pipe replacement. Using
pullers and pulling systems as described, minimally invasive pipe
replacement operations are possible. Reversible pullers are also provided
that decrease the amount of time needed to burst or split multiple
segments of pipe.

Claims:

1. A pulling device, comprising:a puller body having at least one opening
configured to allow a flexible line to pass therethrough;first and second
gear reductions coupled with the puller body, the first and second gear
reductions each including an input and an output;first and second drive
motors, the first drive motor coupled to the input of the first gear
reduction, and the second drive motor coupled to the input of the second
gear reduction; andfirst and second drums, the first drum coupled to the
output of the first gear reduction, and the second drum coupled to the
output of the second gear reduction, the first and second drums
configured to grip and pull the flexible line with rotation of the first
and second drums, wherein the flexible line contacts the first drum
substantially immediately after passing through the opening.

2. The pulling device of claim 1, comprising an intermediate roller
disposed within the puller body between the first and second drums.

3. The pulling device of claim 2, wherein the intermediate roller is
canted with respect to an axis of rotation of at least one of the first
and second drums.

4. The pulling device of claim 2, wherein the intermediate roller includes
a grooved outer surface.

5. The pulling device of claim 1, wherein each of the first and second
gear reductions comprises a harmonic gear reduction.

6. The pulling device of claim 1, wherein each of the first and second
gear reductions comprises a planetary gear reduction.

7. The pulling device of claim 1, wherein the first and second drive
motors are reversible.

8. The pulling device of claim 1, wherein the pulling device is configured
to be coupled with a force distributing device, the force distributing
device being configured to spread at least some reaction forces of the
pulling device across a surface.

9. The pulling device of claim 8, wherein the pulling device is configured
to be coupled with the force distributing device in at least two
different orientations.

10. The pulling device of claim 8, wherein the force distributing device
includes at least two substantially perpendicular force-distributing
surfaces.

11. The pulling device of claim 10, wherein at least one of the
force-distributing surfaces of the force distributing device includes a
slot therein configured to allow the flexible line to pass therethrough.

12. The pulling device of claim 1, wherein at least one of the first and
second drums is hollow.

13. The pulling device of claim 1, wherein the flexible line is wound
around at least one of the first and second drums at least once.

14. A pulling device, comprising:first and second gear reductions coupled
with the pulling device, the first and second gear reductions each
including an input and an output;first and second drive motors, the first
drive motor coupled to the input of the first gear reduction, and the
second drive motor coupled to the input of the second gear
reduction;first and second drums, the first drum coupled to the output of
the first gear reduction, and the second drum coupled to the output of
the second gear reduction, the first and second drums configured to grip
and pull a flexible line with rotation of the first and second drums;
andan intermediate roller disposed within the puller body between the
first and second drums, the intermediate roller canted with respect to an
axis of rotation of at least one of the first and second drums.

15. The pulling device of claim 14, wherein the intermediate roller
includes a grooved outer surface.

16. The pulling device of claim 14, wherein each of the first and second
gear reductions comprises a harmonic gear reduction.

17. The pulling device of claim 14, wherein each of the first and second
gear reductions comprises a planetary gear reduction.

18. The pulling device of claim 14, wherein the first and second drive
motors are reversible.

19. The pulling device of claim 14, wherein the pulling device is
configured to be coupled with a force distributing device, the force
distributing device being configured to spread at least some reaction
forces of the pulling device across a surface.

20. The pulling device of claim 19, wherein the pulling device is
configured to be coupled with the force distributing device in at least
two different orientations.

21. The pulling device of claim 14, wherein at least one of the first and
second drums is hollow.

22. A method of using a pulling device, comprising:routing a flexible line
around at least first and second powered drums of the pulling
device;coupling the pulling device, in a first orientation, to a force
distributing device;placing the pulling device and force distributing
device within a pipe access pit;inserting a first end of the flexible
line through an existing pipe;coupling the first end of the flexible line
to a pipe working tool; androtating at least the first and second powered
drums of the pulling device to pull the flexible line, thereby pulling
the pipe working tool toward the pulling device, wherein the flexible
line is wound directly onto the first powered drum after exiting the
existing pipe.

23. The method of claim 22, comprising:removing the pulling device from
the force distributing device;coupling the pulling device, in a second
orientation, to the force distributing device;inserting a second end of
the flexible line through an existing pipe;coupling the second end of the
flexible line to the pipe working tool; androtating at least the first
and second powered drums of the pulling device in a reverse direction to
pull the flexible line, thereby pulling the pipe working tool toward the
pulling device, wherein the flexible line is wound directly onto the
first powered drum after exiting the existing pipe.

24. The method of claim 22, wherein routing the flexible line around at
least the first and second powered drums includes routing the flexible
line around an intermediate roller disposed within the pulling device
between the first and second drums, the intermediate roller canted with
respect to an axis of rotation of at least one of the first and second
drums.

25. The method of claim 22, wherein placing the pulling device and force
distributing device within the pipe access pit includes:placing a first
force-distributing surface against a first surface of the pit; andplacing
a second force-distributing surface against a second surface of the pit,
wherein the first and second force-distributing surfaces are
substantially perpendicular to each other.

Description:

RELATED APPLICATIONS

[0001]This application claims the benefit of priority, under 35 U.S.C.
§119(e), to U.S. Provisional Patent Application Ser. No. 61/097,372,
filed on Sep. 16, 2008, which is incorporated herein by reference in its
entirety.

[0002]This application is related to U.S. patent application Ser. No.
11/215,316, entitled "DUAL CAPSTAN PULLER AND METHOD", filed Aug. 29,
2005, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

[0003]This invention relates to pulling equipment. Specifically, this
invention relates to pulling equipment for use in trenchless pipe
replacement.

BACKGROUND

[0004]Pipe materials such as cast iron, ductile iron, copper, etc. have
been used for connecting homes and creating networks for utilities such
as water, sewer, or gas, etc. For any number of reasons, an existing pipe
may crack or break, necessitating replacement of the pipe.

[0005]Trenchless pipe replacement is a currently known technique that
replaces underground pipe without the need to dig up the pipe to be
replaced. A pipe breaking device such as an expander, burster, cutter,
etc. is pulled or pushed through the existing pipe while it is still
underground. The pipe breaking device is designed to break or cut the
pipe, and at the same time to expand the old pipe into the surrounding
soil. The expansion of the old pipe allows the pipe breaking device to
concurrently pull a replacement pipe into place.

[0006]Trenchless pipe replacement has typically been employed on large
diameter pipe such as water or sewer main lines. Due to the size of pipe
in these types of replacements, the equipment used for pulling or pushing
the expander through the pipe requires a great deal of force. As a
result, common equipment in the industry for pulling or pushing the
expander is relatively large and expensive such as an above ground winch
and pulley system. These larger scale methods also commonly require a
large access pit to be excavated on at least one end of the pipe to be
replaced.

[0007]More recently, the technique of trenchless pipe replacement has been
employed for smaller diameter pipe such as for lateral lines and even
individual line service to homes such as copper lines. Improved devices
and methods for replacement of these smaller diameter lines are needed as
the industry expands. Some goals for device and method improvement
include lower cost, light weight/portable device designs, and small entry
and exit pits.

SUMMARY

[0008]The above mentioned problems such as low cost, light weight puller
devices and systems adapted for use with small exit and entry pits are
addressed by the present invention and will be understood by reading and
studying the following specification.

[0009]In one example, a pulling device is provided. The pulling device
includes a puller body having at least one opening configured to allow a
flexible line to pass therethrough. First and second gear reductions are
coupled with the puller body. The first and second gear reductions each
include an input and an output. A first drive motor is coupled to the
input of the first gear reduction. A second drive motor is coupled to the
input of the second gear reduction. A first drum is coupled to the output
of the first gear reduction. A second drum is coupled to the output of
the second gear reduction. The first and second drums are configured to
grip and pull the flexible line with rotation of the first and second
drums. The flexible line contacts the first drum substantially
immediately after passing through the opening.

[0010]In another example, a pulling device is provided. The pulling device
includes first and second gear reductions coupled with the pulling
device. The first and second gear reductions each include an input and an
output. A first drive motor is coupled to the input of the first gear
reduction. A second drive motor is coupled to the input of the second
gear reduction. A first drum is coupled to the output of the first gear
reduction. A second drum is coupled to the output of the second gear
reduction. The first and second drums are configured to grip and pull a
flexible line with rotation of the first and second drums. An
intermediate roller is disposed within the puller body between the first
and second drums. The intermediate roller is canted with respect to an
axis of rotation of at least one of the first and second drums.

[0011]In yet another example, a method of using a pulling device is
provided. The method includes routing a flexible line around at least
first and second powered drums of the pulling device. The pulling device,
in a first orientation, is coupled to a force distributing device. The
pulling device and force distributing device are placed within a pipe
access pit. A first end of the flexible line is inserted through an
existing pipe. The first end of the flexible line is coupled to a pipe
working tool. At least the first and second powered drums of the pulling
device are rotated to pull the flexible line, thereby pulling the pipe
working tool toward the pulling device. The flexible line is wound
directly onto the first powered drum after exiting the existing pipe.

[0012]These and other embodiments, aspects, advantages, and features of
the present invention will be set forth in part in the description which
follows, and in part will become apparent to those skilled in the art by
reference to the following description of the invention and referenced
drawings or by practice of the invention. The aspects, advantages, and
features of the invention are realized and attained by means of the
instrumentalities, procedures, and combinations particularly pointed out
in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 shows a perspective view of a pulling system according to an
embodiment of the invention.

[0014]FIG. 2 shows a partially-exploded perspective view of a pulling
system according to an embodiment of the invention.

[0015]FIG. 3 shows a perspective view of a pulling device according to an
embodiment of the invention.

[0016]FIG. 4 shows an end view of a pulling device according to an
embodiment of the invention.

[0017]FIG. 5 shows a side view of a pulling device according to an
embodiment of the invention.

[0018]FIG. 6 shows a side cross-section of a pulling device according to
an embodiment of the invention.

[0019]FIG. 7 shows a side view of a pulling system in operation according
to an embodiment of the invention.

[0020]FIG. 8 shows a method of using a pulling device according to an
embodiment of the invention.

DETAILED DESCRIPTION

[0021]In the following detailed description, reference is made to the
accompanying drawings which form a part hereof, and in which is shown, by
way of illustration, specific embodiments in which the invention may be
practiced. These embodiments are also referred to herein as "examples."
In the drawings, like numerals describe substantially similar components
throughout the several views. These embodiments are described in
sufficient detail to enable those skilled in the art to practice the
invention. Other embodiments may be utilized and structural, or logical
changes, etc. may be made without departing from the scope of the present
invention.

[0022]All publications, patents, and patent documents referred to in this
document are incorporated by reference herein in their entirety, as
though individually incorporated by reference. In the event of
inconsistent usages between this document and those documents so
incorporated by reference, the usage in the incorporated reference(s)
should be considered supplementary to that of this document; for
irreconcilable inconsistencies, the usage in this document controls.

[0023]In this document, the terms "a" or "an" are used, as is common in
patent documents, to include one or more than one, independent of any
other instances or usages of "at least one" or "one or more." In this
document, the term "or" is used to refer to a nonexclusive or, such that
"A or B" includes "A but not B," "B but not A," and "A and B," unless
otherwise indicated. In the appended claims, the terms "including" and
"in which" are used as the plain-English equivalents of the respective
terms "comprising" and "wherein." Also, in the following claims, the
terms "including" and "comprising" are open-ended, that is, a system,
device, article, or process that includes elements in addition to those
listed after such a term in a claim are still deemed to fall within the
scope of that claim. Moreover, in the following claims, the terms
"first," "second," and "third," etc. are used merely as labels, and are
not intended to impose numerical requirements on their objects.

[0024]In the following detailed description, the term flexible line, or
cable includes wire rope, and cables or ropes made from a number of
materials including steel. Although an operation of pipe replacement is
discussed at length in examples below, elements of the invention can be
used in other applications and industries. Some aspects of the invention
are therefore not limited to pipe replacement.

[0025]As discussed in the background above, it is desirable to provide a
puller and pulling system that is lightweight, easy to transport in a
small vehicle such as a pickup truck, etc., and easy for a small work
crew to assemble and use.

[0026]FIGS. 1 and 2 show a pulling system 100 according to an embodiment
of the invention. A pulling device 110, also referred to hereafter as a
puller 110, is shown. As will be discussed in more detail below, the
puller 110 is lightweight and easy to transport, and also highly
powerful, reliable, and easy to operate. In one example, the puller 110
is configured to pull a flexible line 310 (see FIG. 6). Examples of the
flexible line 310 include, but are not limited to, rope, steel cable,
wire rope, etc. In one example, the flexible line 310 includes 5/16-inch
diameter steel cable. In another example, the flexible line 310 includes
3/8-inch diameter steel cable. It is noted that, while specific diameters
of the steel cable are stated above, these sizes of steel cable are not
intended to be limiting, and it should be understood that the puller 110
of the present disclosure can be configured to pull any size of steel
cable, or any other type of flexible line 310. In one example, the puller
110 is configured to be coupled with a force distributing device 130, as
will be described in more detail below.

[0027]As discussed in the background above, there is a need for improved
pullers and systems for small diameter pipe replacement. In one
embodiment, pullers and systems described above are adapted for use with
pipe as small as 1/2'' to 1'' pipe. Examples of pipe that are suitable
for pullers and systems described herein include, but are not limited to,
iron pipe and copper pipe. In one embodiment, a small cable is necessary
to replace such small diameter pipe. In one embodiment a 1/4'' cable is
used.

[0028]When using small diameter cable to burst or split an existing pipe,
one factor to be taken into account in puller designs is that the forces
needed for bursting or splitting are close to a tensile strength of many
possible cable choices. In one embodiment, a constant pulling force
provided by a puller is desirable in contrast to cyclic tugging because
the tensile strength of the cable is less likely to be exceeded. Constant
pulling tends to keep a bursting or cutting head moving and thus subject
to sliding friction within the pipe to be replaced. In contrast, tugging
tends to include several stops and starts on the bursting or cutting
head. Generally starting friction is higher than sliding friction, thus
constant force pulling provides a lower and more consistent bursting or
cutting operation. Design features such as a harmonic drive gear
reduction and other features described below provide a high power,
constant pulling force, and in addition provide low overall device
weight.

[0029]Referring to FIGS. 3 and 4, in one example, the puller 110 includes
a puller body 112 to at least partially enclose components of the puller
110. In one example, the puller body 112 includes first and second plates
112A, 112B attached to opposite ends of a side wall 112C. It is noted
that this configuration of the puller body 112 is but one example and
that other examples including differently constructed configurations of
the puller body 112 are contemplated herein. The puller body 112, in one
example, includes at least one opening 114 configured to allow the
flexible line 310 to pass therethrough. In another example, the puller
body 112 includes more than one opening 114. For instance, in one
example, the puller body 112 includes two openings 114, one opening 114
to allow the flexible line 310 to pass into the puller body 112 and the
other opening 114 to allow the flexible line 310 to exit the puller body
112, for instance, to allow the flexible line 310 to be coiled, spooled,
stacked, or otherwise configured while not being used. In a further
example, the flexible line 310 passes into and out of the puller body 112
through the same opening 114. In one example, except for the one or more
openings 114 for the flexible line 310, the puller body 112 encloses the
components of the puller 110. Advantages of this enclosed configuration
of the puller body 112 include, but are not limited to, enhancing
reliability of the puller 110 by inhibiting incursion of dirt, rocks,
mud, and other debris within the puller 110 and increasing safety during
use of the puller 110 by inhibiting a person contacting moving parts
within the puller 110 with, for instance, a finger or other body part or
a piece of clothing.

[0030]The puller 110, in one example, includes first and second gear
reductions 116, 118 coupled with the puller body 112. The first and
second gear reductions 116, 118 each include an input 116A, 118A and an
output 116B, 118B. In one example, each of the first and second gear
reductions 116, 118 includes a harmonic gear reduction. Use of a harmonic
drive gear reduction provides a number of advantages. One advantage
includes a large mechanical advantage with very little weight in the
device. In one embodiment, a mechanical advantage from the harmonic drive
gear reduction is approximately 200 to 1. Another advantage of a harmonic
drive gear reduction includes a small number of moving parts which in
turn provides a reliable device with fewer parts that could possibly fail
during use. Another advantage of a harmonic drive gear reduction includes
a high number of teeth operatively in contact between an input and output
of the harmonic drive gear reduction. The large number of teeth in
contact provides a high strength to weight ratio of the harmonic drive
gear reduction.

[0031]In another example, each of the first and second gear reductions
116, 118 includes a planetary gear reduction. Use of such a planetary
gear reduction provides a number of advantages, including, for instance,
a large mechanical advantage.

[0032]The puller 110, in one example, further includes first and second
drive motors 117, 119. In one example, the first drive motor 117 is
coupled to the input 116A of the first gear reduction 116, and the second
drive motor 119 is coupled to the input 118A of the second gear reduction
118. In one example, the first and second drive motors 117, 119 are
reversible. In one embodiment, the first and second drive motors 117, 119
include hydraulic drive motors. Other drive motors include, but are not
limited to servo motors or other electrical motors. It is noted that in
some examples, the first drive motor 117 can be a different type of motor
than the second drive motor 119. Additionally, although the puller 110 is
shown herein as including two drive motors and two drive gear reductions,
the invention is not so limited. For instance, the puller 110 can include
more or less than two drive motors and two gear reductions.

[0033]Referring to FIGS. 4-6, the puller 110, in one example, includes
first and second drums 120, 122. In one example, the flexible line 310
wraps around the first and second drums 120, 122 within the puller 110.
When high pulling forces are needed to burst or cut a pipe, equally high
reaction forces such as friction forces are needed within the puller 110.
Multiple drums provide a higher friction surface area, and thus a higher
friction advantage acting on the flexible line 310. Although two drums
120, 122 are shown, a single drum example is also within the scope of the
invention, and examples with more than two drums are also within the
scope of the invention.

[0034]In one example, the first drum 120 is coupled to the output 116B of
the first gear reduction 116, and the second drum 122 is coupled to the
output 118B of the second gear reduction 118. The first and second drums
120, 122 are configured to rotate with the outputs 116B, 118B,
respectively. The first and second drums 120, 122 are configured to grip
and pull the flexible line 310 with rotation of the first and second
drums 120, 122. In one example, the first and second drive motors 117,
119 are reversible to rotate the first and second drums 120, 122 in
either of two directions, thereby allowing pulling of the flexible line
310 in either of two directions, depending upon the direction of rotation
of the first and second drums 120, 122.

[0035]In one embodiment each drum 120, 122 is adapted to accept multiple
windings of the flexible line 310. As discussed above, high friction is
desirable to provide high pulling forces for bursting or cutting. In one
example, five or more windings are used on a drum to increase friction.
In one example, the flexible line 310 is wound around at least one of the
first and second drums 120, 122 at least once to increase friction
between the flexible line 310 and at least one of the first and second
drums 120, 122. In one example, the first and second drums 120, 122
include a friction surface that includes space for multiple windings of a
cable or other flexible line 310. Although the cable contacting surfaces
of the drums 120, 122 can be flat, in one example, cable grooves are
formed into the drums. Grooves further increase contact surface area that
in turn increases friction with the cable. In one example, the friction
surface of at least one of the first and second drums 120, 122 includes
grooves 120A, 122A configured to accommodate the flexible line 310
therein in order to facilitate winding of the flexible line 310 at least
partially around at least one of the first and second drums 120, 122. As
seen in FIG. 5, in one example, at least one of the first and second
drums 120, 122 is hollow. In another example, both of the first and
second drums 120, 122 are hollow. Advantages of at least one of the first
and second drums being hollow include weight savings in the puller 110,
making the puller 110 and pulling system 100 lighter and, in turn,
generally more manageable during transport, carrying, setting-up, etc.

[0036]FIG. 6 shows a cross section of a puller 110 according to an example
of the invention with the flexible line 310 routed through the puller
110. A first end 312 and a second end 314 of the flexible line 310 are
shown at entry/exit locations of the puller 110. In one embodiment, the
puller 110 is reversible, such that the first end 312 or the second end
314 could be used as either an entry or exit location of the puller 110
depending on the direction of puller operation.

[0037]In one example, the first drum 120 is positioned within the puller
110 proximate the at least one opening 114 in the puller body 112. In one
example, the flexible line 310 contacts the first drum 120 substantially
immediately after passing through the opening 114 during pulling of the
flexible line 310. That is, the flexible line 310 contacts the first drum
120 shortly after, if not immediately after, passing into the puller 110
through the opening 114. In one example, the flexible line 310 is wound
directly onto the first drum 120 after entering the puller body 112. By
configuring the puller 110 to wind the flexible line 310 directly onto
the first drum 120, no guide rollers, drums, pins, or the like are
required to route the flexible line 310 from outside of the puller body
112 onto the first drum 120, thereby reducing or eliminating a possible
source of system losses, such as from friction or heat. By reducing or
eliminating such system losses, the puller 110 has an increased
efficiency, such that more pulling power is transferred into the job,
rather than incurring system losses as a result of additional pulleys,
guide wheels, etc.

[0038]Referring to FIG. 5, the puller 110, in one example, includes an
intermediate roller 124 disposed within the puller body 112 between the
first and second drums 120, 122. In one example, the intermediate roller
124 is canted with respect to an axis of rotation 120' or 122' of at
least one of the first and second drums 120, 122. For instance, as shown
in FIG. 5, an axis of rotation 124' of the intermediate roller 124 is
canted by an angle A from a line X, which is parallel to at least one of
the axes of rotation 120', 122' of the first and second drums 120, 122.
In one example, the intermediate roller 124 rotates about an intermediate
axle 125. Bearings 126 are used in one example to facilitate rotation of
the intermediate roller 124 about the intermediate axle 125. In various
examples, the bearings 126 include ball bearings, roller bearings, ball
thrust bearings, roller thrust bearings, or tapered roller thrust
bearings. In other examples, no bearings are used and, instead, bushings
or other such friction-reducing members are used to facilitate rotation
of the intermediate roller 124 about the intermediate axle 125. In yet
another example, the intermediate roller 124 rides directly on the
intermediate axle 125.

[0039]In one example, the intermediate roller 124 includes a grooved outer
surface 124A. The grooved outer surface 124A allows for a prescribed wind
pattern of the flexible line 310 on the intermediate roller 124. In one
example, the grooved outer surface 124A includes one generally
spirally-wound groove extending around the intermediate roller 124. In
another example, the grooved outer surface 124A includes several grooves
extending around the intermediate roller 124. The groove or grooves of at
least some of the examples of the grooved outer surface 124A are
configured to accommodate the flexible line 310 at least partially
therein.

[0040]As described above, in one example, the intermediate roller 124 is
canted. By canting the intermediate roller 124 in this way, forces on the
intermediate roller 124, for instance, from the flexible line 310 at
least partially wound therearound, can be lessened. For instance, such a
canted configuration can reduce frictional forces between the
intermediate roller 124 and the bearings 126, the bushing, or the
intermediate axle 125. By reducing such frictional forces, wear and tear
of the puller 110, specifically that of the intermediate roller 124 and
the components thereof, can be lessened and the life of the puller 110
can be extended. Additionally, in one example, by canting the
intermediate roller 124, the grooves of the grooved outer surface 124A
align the grooves 120A, 122A of the first and second drums 120, 122 to
reduce cable wear and groove wear. That is, canting the intermediate
roller 124 aligns the grooves 120A, 122A of the first and second drums
120, 122 and the grooved outer surface 124A of the intermediate roller
124 to reduce, if not eliminate, the amount that the flexible line 310
wears against the grooves 120A, 122A and the grooves of the grooved outer
surface 124A, thereby reducing cable wear and groove wear.

[0041]The examples of pulling devices 110 described herein provide high
constant pulling forces, in contrast to a tugging force. High amounts of
friction are provided using designs described herein in a small device
that is light weight. Devices as described herein therefore have a high
power to puller weight ratio, and a high power to puller volume ratio.

[0042]Referring now to FIGS. 1, 2, and 7, in one example, the pulling
device 110 of the pulling system 100 is configured to be coupled with a
force distributing device 130. In one example, the force distributing
device 130 is configured to spread at least some reaction forces of the
pulling device across a surface. The surface can include any surface upon
which the pulling device 110 may be placed, including, but not limited
to, a surface of a surface of a pit 402 within which the puller device is
placed for pipe extraction or replacement.

[0043]In one example, the pulling device 110 is coupled to the force
distributing device 130 using an engaging feature 160 such as a
protruding pin. In another example, a releasable capture device 160 is
used to accept and hold the engaging feature 120. Releasable capture
devices 120 include, but are not limited to levers, clasps, other
mechanical devices, electro-mechanical devices, and the like. In still
another example, the pulling device 110 is coupled with the force
distributing device 130 using one or more spring-loaded pins 160. In one
example, a number of spring-loaded pins 160 are used in combination with
holes 111A, 111B in the puller body 112 to facilitate adjustments. In one
example, the force distributing device 130 includes two spring-loaded
pins 160 used in combination with a first pair of holes 111A in the
puller body 112 or a second pair of holes 111B in the puller body 112.

[0044]In one example, each of the spring-loaded pins 160 includes a
housing 161 attached to the puller body 112 in some manner, including,
but not limited to a threaded coupling, use of one or more fasteners,
welding, or the like. The spring-loaded pin 160 includes a post portion
162 coupled to a pin 164. In this example, the post portion 162 is in the
form of a T-handle to facilitate pulling of the pin 164 from within one
of the holes 111A, 111B. A spring 166 is disposed around the pin 164
between a shoulder 164A of the pin 164 and an end of the housing 161 to
bias the pin 164, such that the pin 164 is normally seated within one of
the holes 111A, 111B. A slot 161A is included in this example that
substantially matches the post portion 162 to provide an engaged position
of the pin 164 when the post portion 162 is within the slot 161A. In one
example, the pin 164 is pulled against the bias of the spring 166 and
rotated so that the post portion 162 sits outside the slot 161A, as shown
in FIG. 1, when it is desired to uncouple the pulling device 110 from the
force distributing device 130. With the post portion 162 resting on the
end of the housing 161, outside the slot 161A, the pin 164 is disengaged
from any holes 111A, 111B, and the pulling device 110 can be removed,
moved, repositioned, or otherwise maneuvered with respect to the force
distributing device 130. In one example, to engage the pin 164 of the
spring-loaded pin 160, the post portion 162 is rotated to line up with
the slot 161A to allow the spring 166 to bias the pin 164 into engagement
with one of the holes 11A, 11B. Adjustment of the pulling device 110 is
facilitated with this configuration because a user does not have to hold
the pin 164 against the bias of the spring 166 while adjustment of the
pulling device 110 is being performed. Moreover, a simple twist of the
post portion 162 returns the spring-biased pin 164 into one of the holes
111A, 111B and into engagement with the pulling device 110.

[0045]An advantage of spring-loaded pins 160 includes the security and
mechanical robustness of a pin-in-hole adjustment, combined with
convenience of a pin that is less likely to get lost or dropped during an
adjustment because of its attachment to the puller body 112. It is noted
that this is but one configuration of an example of the spring-loaded
pins 160 and that further examples of spring-loaded pins having different
configurations could be used in place of the above-described
spring-loaded pins 160. Moreover, attachment devices other than the
above-described spring-loaded pins 160 are contemplated herein, such as,
but not limited to, non spring-loaded pins, fasteners such as bolts or
nut and bolt combinations, and the like.

[0046]In one example, because the holes 111A, 111B are formed as
through-holes in the pulling device 110, dirt or other debris often found
on job sites is able to be forced or otherwise move out of the holes
111A, 111B and clear of the pin 164 during an adjustment of the pulling
device 110 with respect to the force distributing device 130. This
configuration provides one level of improvement over closed designs that
may jam due to the presence of dirt and the like.

[0047]In one example, the pulling device 110 is configured to be coupled
with the force distributing device 130 in at least two different
orientations of the pulling device 110. For instance, the pulling device
110, in a first orientation, can be configured to allow the pulling
device 110 to pull the flexible line 310 through one of the openings 114
(see FIG. 4) and, in a second orientation, can be configured to allow the
pulling device 110 to pull the flexible line 310 through another one of
the openings 114 (see FIG. 4).

[0048]Referring now to FIGS. 1 and 2, in one example, the pulling device
110 includes an engagement feature 113 for coupling the pulling device
110 to the force distributing device 130. In one example, the engagement
feature 113 is a rod 113 disposed within holes 111C in the puller body
112 of the pulling device 110. In this example, the rod 113 is configured
to fit within mounting notches 132 of the force distributing device 130.
Engagement of the rod 113 within the mounting notches 132 of the force
distributing device 130 effectively restrains a bottom of the pulling
device 110. The spring-loaded clips 160, as described above, can then be
selectively engaged with the holes 111A to attach the pulling device 110
in the first configuration or with the holes 111B to attach the pulling
device 110 in the second configuration. It should be understood that
engagement features 113 other than the rod 113 could be used in other
examples of the pulling device, provided the different engagement
features 113 are capable of at least assisting in restraining the pulling
device within the force distributing device 130. For instance, in another
example, the engagement feature 113 is an integral tab of the puller body
112 that is configured to fit within a complementary notch in the force
distributing device 130.

[0049]In one example, the pulling device 110 includes another rod 115
disposed within holes 111D in the puller body 112. In one example, the
holes 111D and the rod 115 are disposed between the holes 111A and 111B
at a top end of the puller body 112, opposite the bottom end. The rod 115
of this example provides a grip for the user to lift, handle, manipulate,
or carry the pulling device 110. Additionally, the rod 115 provides a
connection point for a strap, rope, hook, or the like, for use in
lowering the pulling device 110 into the pit 402, for instance.

[0050]Referring again to FIGS. 1, 2, and 7, in one example, the force
distributing device 130 is configured to spread at least some reaction
forces of the pulling device 110 across a surface. In one example, the
force distributing device 130 includes a first force-distributing surface
140 and a second force-distributing surface 150. When placed within a
pipe access pit 402, in one example, the first force-distributing surface
140 is placed against a first surface 402A, and the second
force-distributing surface 150 is placed against a second surface 402B.
In this example, any downward reaction forces of the pulling device 110
are distributed across the first force-distributing surface 140, and any
lateral reaction forces of the pulling device 110 are distributed across
the second force-distributing surface 150. In one example, the first and
second force-distributing surfaces 140, 150 are substantially
perpendicular to one another. In other examples, the first and second
force-distributing surfaces 140, 150 are oriented at different angles
with respect to one another other than perpendicular in order to
accommodate first and second surfaces 402A, 402B of the pit 402 that are
not roughly perpendicular. In still other examples, it is contemplated
that the angle between the first and second force-distributing surfaces
140, 150 is adjustable.

[0051]In one example, at least one of the force-distributing surfaces 140,
150 of the force distributing device 130 includes a slot 134 therein
configured to allow the flexible line 310 to pass therethrough. In one
example, a first portion 134A of the slot 134 is disposed through the
first force-distributing surface 140, and a second portion 134B of the
slot 134 is disposed through the second force-distributing surface 150.
In one example, the first portion 134A of the slot 134 extends across an
entire length of the first force-distributing surface 140. In another
example, the second portion 134B of the slot 134 extends only partially
along the length of the second force-distributing surface 150. In a
further example, the slot 134 includes a third portion 134C through the
second force-distributing surface 150, which is essentially a through
hole at the end of the second portion 134B of the slot 134. The third
portion 134C, in one example, is wider than the second portion 134B of
the slot 134.

[0052]In one example, the slot 134 accommodates the flexible line 310 and
allows the pulling device 110 having the flexible line 310 routed
therethrough to be attached to the force distributing device 130. That
is, the pulling device 110 can be attached to the force distributing
device 130 without uncoupling the flexible line 310 from the pulling
device 110 or threading the entire length of the flexible line 310
through an opening in the force distributing device 130. Instead, in this
example, only a portion of the flexible line 310 extending from the
pulling device 110 is passed through the first and second portions 134A,
134B of the slot 134 while coupling or reconfiguring the pulling device
110 with the force distributing device 130. The flexible line 310 can
then be passed into the third portion 134C of the slot 134 for operation
of the pulling system 100.

[0053]FIG. 7 shows one example of a pipe bursting or cutting operation
using pulling systems 100, devices, and components as described above.
The pulling system 100 is shown including the force distributing device
130. First and second pits 402, 404 are created below a ground surface
400. In one example, the surface 400 includes a paved roadway. The first
and second pits 402, 404 are shown for exit and entry of a replacement
pipe 430. In one example, the pulling system 100 is placed within the
first pit 402 with the first force-distributing surface 140 in contact
with a first surface 402A and the second force-distributing surface 150
in contact with a second surface 402B. An existing pipe 420 is shown in
place with a bursting head 410 partially through a bursting operation. A
section of burst pipe 422 is shown behind the bursting head 410 with the
replacement pipe 430 being pulled in behind. FIG. 7 shows a bursting heat
410 that is adapted to split a ductile pipe in addition to expanding the
pipe into the surrounding soil, however the invention is not so limited.
A flexible line 310 is coupled to the bursting head 410. The flexible
line 310 is being pulled by the pulling system 100 through the existing
pipe 420.

[0054]It is desirable when replacing a pipe to cause minimal damage to
existing surfaces such as roadways. In one example, pullers and puller
systems as described above are capable of pipe replacement using a
relatively small pit 402. The puller 110 and force distributing device
130 described above can be constructed to be relatively small and
compact, thereby enabling a relatively small pit 402 to be used with the
pulling system 100. Because the pit 402 can be relatively small when
using pullers 110 and systems 100 described above, the resulting patch in
the surface 400, once pipe replacement is complete, is small.

[0055]In one embodiment, the pit 402 is formed in a paved roadway. Because
the pit is relatively small, higher quality patch materials can be used
economically. In one method, epoxy based patch materials are used to
patch pits in paved roadways. Such high quality patches do not wear out
as quickly as lower quality patch materials and, therefore, lessen the
likelihood that such patches will cause uneven roadways after pipe
replacement.

[0056]As discussed above, in one embodiment, the puller 110 is reversible.
One advantage of a reversible puller 110 includes a time savings in
bursting or cutting operations. After a flexible line 310 is pulled
through an existing pipe 420 to complete an operation, the end of the
flexible line 310 can be reinserted into the next segment of existing
pipe to be replaced without reversing the flexible cable 310 all the way
through the puller 110. There is no need to re-thread the cable over the
drums of the puller 110. In reversible embodiments, the puller 110 is
simply re-oriented on the force distributing device 130. The puller 110
is then operated with the drive motors in the reverse direction. This
process can be repeated as many times as necessary to burst or split
several consecutive segments of pipe.

[0057]Referring to FIG. 8 (with additional reference to FIGS. 1, 5, 6, and
7), in another example, a method 1000 of using a pulling device 110
includes, at 1010, routing a flexible line 310 around at least first and
second powered drums 120, 122 of the pulling device 110. In one example,
at 1020 the pulling device 110 is coupled, in a first orientation, to a
force distributing device 130. In one example, as described above,
spring-loaded pins 160 are used to engage within holes 111A of the puller
body 112 to couple the pulling device 110 in the first orientation with
respect to the force distributing device 130. At 1030, the pulling device
110 and force distributing device 130 are placed within a pipe access pit
402. At 1040, a first end of the flexible line 310 is inserted through an
existing pipe 420. At 1050, the first end of the flexible line 310 is
coupled to a pipe working tool 410. At 1060, at least the first and
second powered drums 120, 122 of the pulling device 110 are rotated to
pull the flexible line 310, thereby pulling the pipe working tool 410
toward the pulling device 110. In one example, the flexible line 310 is
wound directly onto the first powered drum 120 after exiting the existing
pipe 420. That is, in this example, the flexible line 310 is wound onto
the first powered drum 120 immediately or substantially immediately after
passing through an opening 114 in the puller body 112.

[0058]In one example, the method 1000 further includes removing the
pulling device 110 from the force distributing device 130. For instance,
in one example, the spring-loaded clips 160 are disengaged from within
the holes 111A to allow removal of the pulling device 110 from the force
distributing device 130. The pulling device 110 is then coupled, in a
second orientation, to the force distributing device 130. For instance,
the spring-loaded clips 160 can be re-engaged with the holes 111B to
couple the pulling device 110, in the second orientation, to the force
distributing device 130. A second end of the flexible line 310 is
inserted through another existing pipe 420. The second end of the
flexible line 310 is coupled to a pipe working tool 410. At least the
first and second powered drums 120, 122 of the pulling device 110 are
rotated in a reverse direction (that is, in a direction opposite the
rotational direction of the first and second powered drums 120, 122 when
the pulling device 110 is attached to the force distributing device 130
in the first orientation) to pull the flexible line 310, thereby pulling
the pipe working tool 410 toward the pulling device 110. In one example,
the flexible line 310 is wound directly onto the first powered drum 120
after exiting the existing pipe 420. That is, as with the above example,
the flexible line 310 is wound onto the first powered drum 120
immediately or substantially immediately after passing through another
opening 114 in the puller body 112.

[0059]In one example, routing the flexible line 310 around at least the
first and second powered drums 120, 122 includes routing the flexible
line 310 around an intermediate roller 124 disposed within the pulling
device 110 between the first and second drums 120, 122. In one example,
as described above, the intermediate roller 124 is canted with respect to
an axis of rotation 120' or 122' of at least one of the first and second
drums 120, 122.

[0060]In one example, placing the pulling device 110 and force
distributing device 130 within the pipe access pit 402 includes placing a
first force-distributing surface 140 against a first surface 402A of the
pit 402 and placing a second force-distributing surface 150 against a
second surface 402B of the pit 402. In this example, the first and second
force-distributing surfaces 140, 150 are substantially perpendicular to
each other. In other examples, the first and second force-distributing
surfaces 140, 150 are oriented at different angles with respect to one
another. In still other examples, it is contemplated that the angle
between the first and second force-distributing surfaces 140, 150 is
adjustable in order to accommodate first and second surfaces 402A, 402B
of the pit 402 that are not roughly perpendicular.

[0061]Pullers and systems using pullers as described above can be made
very lightweight and portable. In one embodiment, a puller system weighs
less than 65 lbs. and can be disassembled into a number of component
parts. Even a single user is therefore easily able to move such a puller
or puller system in a small vehicle such as a pickup truck to a job site
and assemble the puller system.

[0062]The above description is intended to be illustrative, and not
restrictive. For example, the above-described examples (or one or more
aspects thereof) may be used in combination with each other. Combinations
of the above embodiments, and other embodiments will be apparent to those
of skill in the art upon reviewing the above description. Other
embodiments can be used, such as by one of ordinary skill in the art upon
reviewing the above description. While a number of advantages of
embodiments described herein are listed above, the list is not
exhaustive. Other advantages of embodiments described above will be
apparent to one of ordinary skill in the art, having read the present
disclosure. Although specific embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill in
the art that any arrangement which is calculated to achieve the same
purpose may be substituted for the specific embodiment shown. This
application is intended to cover any adaptations or variations of the
present invention.

[0063]The Abstract is provided to comply with 37 C.F.R. §1.72(b), to
allow the reader to quickly ascertain the nature of the technical
disclosure. It is submitted with the understanding that it will not be
used to interpret or limit the scope or meaning of the claims. Also, in
the above Detailed Description, various features may be grouped together
to streamline the disclosure. This should not be interpreted as intending
that an unclaimed disclosed feature is essential to any claim. Rather,
inventive subject matter may lie in less than all features of a
particular disclosed embodiment. Thus, the following claims are hereby
incorporated into the Detailed Description, with each claim standing on
its own as a separate embodiment. The scope of the invention includes any
other applications in which the above structures and fabrication methods
are used. The scope of the invention should be determined with reference
to the appended claims, along with the full scope of equivalents to which
such claims are entitled.